Various one-dimensional and multi-dimensional (nD) nuclear magnetic resonance (NMR) spectroscopy techniques are presently utilized for elucidating the structure of chemical species. One-dimensional (1D) NMR experiments can provide basic information regarding a sample molecule under investigation such as chemical shifts, sizes of J coupling constants, and relative numbers of nuclear spins. Two-dimensional (2D) NMR experiments provide further elucidation such as connectivity or coupling patterns among spins, and generally resolve information that is left ambiguous or undetected by 1D experiments. NMR experiments of higher dimension (e.g., 3D, 4D, etc.) can provide even further structural elucidation and facilitate the study of spin systems involving three or more nuclei of different types.
A given NMR experiment entails the selection and use of a radio-frequency (RF) pulse sequence that is applied to the sample under investigation via a transmitter coil to generate an observable RF free induction decay (FID) response signal of time domain. The FID signal is detected by a receiver coil and processed by associated receiver electronics. The FID signal is digitized and further processed through one or more dimensional Fourier Transformation (FT) to produce a spectrum of frequency domain from which structural information regarding the sample can be determined. A wide range of pulse sequences or recipes are available for different purposes. Complete elucidation of molecular structure, particularly secondary structure, has conventionally required the successive recording of a number of different NMR experiments to produce a number of different spectra needed for rendering a full analysis of the molecule. This has been due in part to the limited utility of presently known pulse sequences and the limitations of conventional NMR receiver hardware and software. The execution of multiple NMR experiments is disadvantageous for a number of reasons. The carrying out of successive NMR experiments can take a long time, increases the probability of human error and variation in the operating conditions of the NMR spectroscopy apparatus from one experiment to the next, and does not ensure that all spectra are recorded under identical conditions.
A need therefore exists for a single, comprehensive or “all-in-one” NMR experiment capable of recording all of the information necessary for analyzing the structure of a sample molecule with the use of one pulse sequence.